HTC M8 and PPSSPP

[MilTora]

Hello,
First of all, I want to apologise if this isn't the right forum to ask this, but I recently bought an HTC M8 and I installed SkyDragon's Sense 7 ROM (5.0.2).
I downloaded last PPSSPP build and started playing KH BBS. The game runs fine but sometimes it slows down hard when in a big map or when lots of enemies spawn.
I wonder if there is any way to improve my phone's performance. Is there a noticeable difference between 5.0.2 Sense ROMs and 5.1 GPe regarding PPSSPP performance? Is there any optimal setting I should be using?
Also, I've read many times that Qualcomm Drivers are a huge issue right now, is that still true?
Thanks in advance